Fault Trajectories and Location Estimations for Distance Protection using two New Simplified Phasor Analysers

Abstract

The paper presents two new computationally simple algorithms for the protection of power transmission lines during fault conditions. The first method is based on the minimisation of a weighted forgetting factor based error cost function by the use of a fast Gauss-Newton method approach. Further a Hessian matrix approximation is used to produce a fast recursive algorithm, which is immune to random noise, waveform distortion due to DC offsets and increases the speed of convergence and accuracy. The algorithm models the typical time-varying signal and the accompanied distortions due to harmonics and random noise in a manner that will be suitable for real-time apparent impedance estimation. The second approach is based on a phase corrected wavelet transform known as fast discrete S-transform, which unlike the conventional one, uses frequency selection and frequency localised band pass filtering techniques to reduce the computational overhead and makes it suitable for on-line implementation in computing the fault location on an overhead transmission line. Both the proposed schemes are evaluated for the protection of a transmission line in a meshed power system network for a variety of fault types, fault locations, fault resistances, and significant noise in the signal using computer simulation studies.